Myocardial decompensation is a serious complication of a number of forms of human shock. Two important conditions in which its overt or occult presence can cause major difficulties in resuscitation are in the immediate recovery period following cardiopulmonary bypass for coronary artery surgery, and in the course of severe sepsis following surgical illness. This grant is a combined clinical and experimental study which seeks to integrate basic research on the interrelations between myocardial regional bloodflow (using a thermal clearance method), transmural myocardial electrical conduction velocities and myocardial contractile responses with myocardial substrate metabolism (using field ionization mass spectrometry of non-radioactive isotopic labeled compounds), during and after a period of hypothermic myocardial protection. Studies are to be carried out in an experimental in vivo myocardial pedicle preparation and in clinical coronary bypass grafting (CABG). Similar studies will also be carried out in an experimental myocardial sepsis model, and in human sepsis. As a means of quantifying and predicting human cardiovascular responses to CABG and in septic myocardial depression, a new analytic technique of multivariable time series analysis is being developed and applied to computer-based analysis of continuously monitored clinical cardiovascular and respiratory data. These responses will be used as part of a multivariable statistical evaluation of the role of myocardial substrate utilization in modifying recovery after hypothermic myocardial preservation, or after septic myocardial depression.